It's not that unbalanced.... usually by midgame the tradeoff for a cargo ship is something like 8 food or 15 gold and 2 science.
For your first trade route or two, gold is so scarce it's kind of hard to pass up 8 gold 3 science for 6 food. Especially since you need a couple of ships to maintain that trade route (which cost gold to maintain).
I will take the +6 food anytime. The comparison isn't even close. Food is transfered into science and hammers for your cities. More population brings more gold later. The evidence is clear, at least for me. I still think that these early food trades are OP.
Starting near all that salt, in your example Tabarnak, is what I would call OP. 4 salt resources in adjacent tiles, as well as crab and gold nearby? For reals?!?! That is awesome.
No cities are riversided...but yeah 4 salts is still awesome. Still, you can compare better starts(deserts with adjacent mountain, marble,etc)
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What some people still don't understand is the food/hammer/gold/ratio. And for now the ratio is way too unbalanced.
Food>Hammers>Gold
Food can be transfered into population, which gives more science and production(buildings), which lead to more gold.
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You can generate gold with ambassies(1 gpt), you can sell ressources(horses and iron) in grapes of 3 or 4 for 4 or 5 gpt respectively, you can also sell luxs for 6 gpt(if they have enough gpt). Meanwhile, it's preferably better to concentrate on growth(population), the milk cow of civ games.